Terpolymerization of Substituted Cycloolefin with Ethylene and Norbornene by Transition Metal Catalyst
Year: 2016
Type: article
Abstract: Ethylene-norbornene terpolymerization experiments using 5-alkyl-substituted norbornenes (5-pentyl-2-norbornene (C5N) and 5-octyl-2-norbornene (C8N)) or dicyclopentadiene (DCPD) were conducted with two ansa-metallocenes, [Zr{(η5-C9H6)2C2H4}Cl2] (1) and [Zr{(η5-2,5-Me2C5H2)2CHEt}Cl2] (2), activated by methylaluminoxane (MAO). The terpolymers obtained were investigated in detail by determining the microstructure and termonomer contents by 13C NMR, molar masses and thermal properties. Results were compared to those of ethylene (E)-norbornene (N) terpolymerizations with 1-octene. 2, with lower steric hindrance and a shorter bridge, gave the best activities, termonomer incorporation and molar masses. The size of the substituent in 5-alkyl substituted norbornene also plays a role. C8N gives the highest activities and molar masses, while DCPD terpolymers have the highest cycloolefin content. Terpolymers are random; their molar masses, much higher than those in 1-octene terpolymers, are in a range useful for industrial applications. Finally, Tg values up to 152 °C were obtained. For similar N content, poly(E-ter-N-ter-C8N)s and poly(E-ter-N-ter-DCPD)s have the lowest and the highest Tg values, respectively. Thus, the presence of an eight-carbon atom pendant chain in C8N increases the flexibility of the polymer chain more than a five-carbon atom pendant chain in C5N. The higher rigidity of C5N may lead to lower activities and to increasing probability of σ-bond metathesis and chain termination, as evidenced by chain-end group analysis.
Source: Polymers
DOI: 10.3390/polym8030060
Language: English
Subfield: Organic Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,258
OpenAlex ID: W2283462915